The gang burst on to a runway in fake police vehicles with blue lights flashing.

They got onto the airport site by driving through a hole that had been cut in a fence.

Eight men in masks piled out and pointed their assault rifles’ infra-red sights at staff loading the plane’s hold.

The thieves quickly found a shoebox-sized container packed with precious stones. They then fled at high speed back through the hole in the fence.

The raid at Brussels Airport in Belgium on Monday was over in three minutes and most of the Switzerland-bound plane’s passengers were unaware it had been robbed.

A police source said yesterday: “Gold was also taken, but the robbers clearly knew about the diamonds, and where they were. The way they got on to the secure runways area suggests that they had inside help.”

Not a shot was fired. A Mercedes people-carrier the gang used was found burned-out, less than an hour later. An Audi car they also used is missing.